Method of treating gelatin



Patented Apr. 4, 1939 UNITED STATES PATENT OFFlE heim, Germany,

assignors to firm Carl Freudenberg G. in. b. H., Weinheim, Germany, a societyof Germany No Drawing. Application May 4, 1935, Serial No. 19,902. In Germany May 4, 1934 14 Claims. (01. 106-39 It is known to make gelatin more or less soft or elastic by the incorporation of substances which are soluble in water, such as glycerine, and, in some cases, mixtures of glycerine and water. Gelatin treated in this Way retains its elastic properties after washing and subsequent drying.

It is also known to incorporate glycerine into the gelatin together with neutral or acid esters of polyhydric alcohols of the fatty acid series-and organic acids in which case, the glycerine, which is easily removed by water, stillremain's in' the gelatin. Finally, it has also already been proposed to incorporate esters of the said type into gelatin without the addition of glycerine. This method presents difficulties, however, and does not lead to sufiiciently satisfactory results.

The underlying idea of the present invention consists in bringing the gelatin first of all to such a state that it can uniformly take up softening agents which contain little or no water and which are insoluble or practically insoluble in water such as castor oil, train oil and so on and, if desired,

further substances such as varnish made from cellulose esters and the like. This can be done, for example, by swelling gelatin, preferably in a more or less finely divided state, for example in a granulated state, by treatment with non-aqueous organic swelling agents, for example, glycerine or mixtures of glycerine and other organic liquids, for example, organic solvents such as methyl alcohol and, after substantially removing the swelling agent, incorporating a softening agent into the gelatin which is insoluble in water. The action of the swelling agent can be improved by heating. The removal of the swelling agent can be effected, for example, with the help of suitable volatile solvents such as methyl alcohol. The incorporation of the softening agent (which, preferably, is one which can be melted) can be carried out by the usual methods such as kneading, pressing and so on. The gelatin softened in accordance with the invention can be made by usual methods into any desired objects such as sheets, bands and so on. This can 5 be done, for example, by passing the gelatin in the warm state through presses, through suitably shaped nozzles, through rollers, by extruding it or like measures.

Alternatively, objects manufactured from untreated gelatin, for example, in the form of sheets and so on, can be swollen and, after a more or less thorough removal of the swelling agent, softening agents which are insoluble in water can be incorporated into them. This can be effected, for example, by rubbing in, pressing in and like methods and, if need be, with the application of heat.

The objects can be made to hold their shape and have their properties modified by the usual methods such as tanning, for example, by means of fats, 5 hardening, for example, by means of formalin, and so on. These steps can be carried out before, during or after incorporation of the softening agent.

The method in accordance with the invention 1 can also be used with gelatin and gelatin objects whichv contain amounts of other substances in inconsequential amounts. Also, gelatin containing fibrous substances in inconsequential amounts can also be treated in accordance with the inven- 15 (1) 50 grammes of granulated gelatin are swollen for twelve hours in 180 cubic centimetres of Water-free glycerine and 20 cubic centimetres 20 of methyl alcohol. The excess glycerine mixture is then removed by centrifuging and the swollen grains are maintained for about one hour at 40 to 50 C. The granulated material is then freed of glycerine by one or more treatments with concen- 25 trated alcohol, for example, 96% alcohol, and 200 grammes of castor oil are then incorporated into it by rubbing or rolling the oil into the material. After expression of the excess castor oil, the mass is melted at to C. and is converted into objects of the desired shape, for example by extrusion through suitable nozzles. After cooling, the objects are subjected to further treatment such, for example, as hardening with formalin.

2) Gelatin films manufactured in the usual 35 manner are swollen by being soaked at 20 C. in a mixture of equal parts of glycerine and methyl alcohol. The alcohol is then evaporated off by heating to 40 C. so that the gelatin film is obtained in an unshrivelled state. The glycerine is then removed, for example by washing with methyl alcohol and the film is then soaked in cod liver oil and the oxidation is carried out by exposing the softened material for a certain length of 45 time to the air.

(3) An unhardened gelatin film is treated for twelve hours in a mixture of cubic centimetres of water free glycerine and 20 cubic centimetres of methyl alcohol. After superficial re- 50 moval of the glycerine-alcohol mixture, the film is heated for about two hours at 40 to 50 C. and, after cooling, is freed from glycerine by treatment with about 200 cubic centimetres of 96% methyl alcohol. About five grammes of cod liver 55 oil is then rubbed into the film and the film is subjected to oxidation by allowing it to stay in the air at about 45 C. After the tanning which is thus effected, films are obtained having permanent elastic qualities.

We claim:

1. A method of treating gelatin comprising swelling the gelatin with a non-aqueous glycerine-containing swelling agent, substantially removing the swelling agent from said gelatin by extraction with a volatile organic solvent which dissolves glycerine and incorporating a softening oil which is insoluble in water into the gelatin.

2. A method of treating gelatin according to claim 1, in which the swelling agent consists of glycerine.

3. A method of treating gelatin according to claim 1, in which the swelling is carried out with the application of heat.

4. A method of treating gelatin according to claim 1, in which the said softening oil consists of castor oil.

5. A method of treatng gelatin according to claim 1, in which the said softening oil consists of train oil.

6. A method of treating gelatin according to claim 1, in which the gelatin is treated with the swelling agent while in a granulated state.

7. A method of treating a gelatinous object comprising subjecting the object to the action of a non-aqueous glycerine-containing swelling agent, substantially removing the swelling agent by extraction with a volatile organic solvent 3 which dissolves glycerine and incorporating therein a non-aqueous softening oil which is insoluble in water.

8. A method of treating gelatin comprising subjecting the gelatin to the swelling action of a mixture of glycerine and methyl alcohol, sub-' stantially removing the swelling agent from said gelatin by extraction with a volatile organic solvent which dissolves glycerine and incorporating a non-aqueous softening oil which is insoluble in water into the gelatin.

9. A method of treating gelatin according to claim 1, comprising removing the swelling agent by means of methyl alcohol.

10. A method of treating gelatin films according to claim 1, in which varnish made from cellulose ester is incorporated into the swollen gelatin in addition to said softening oil.

11. A method of treating a gelatinous object according to claim 7, in which varnish made from cellulose ester is incorporated into the swollen object in addition to said softening oil.

12. A method of treating a gelatinous object according to claim 7, comprising subjecting the object to the action of formalin after removal of the glycerine-containing swelling agents.

13. A method of treating a gelatinous object according to claim 7, comprising subjecting the object to the action of a tanning agent after removal of the glycerine-containing swelling agents.

14. As a new composition of matter, a glycerine-swelled gelatin, substantially free from glycerine and containing a sufiicient quantity of finely dispersed, water-insoluble softening oils of the class consisting of castor oil, train oil, and cod liver oil, to maintain the composition permanently in a soft and elastic condition.

EGON ELtiD. ERNST DEMME. 

